appdx-scriptops.asciidoc

Appendix A: Transaction Script Language Operators, Constants, and Symbols

Note	Tables and descriptions sourced from https://en.bitcoin.it/wiki/Script.

Push value onto stack shows operators for pushing values onto the stack.

Table 1. Push value onto stack

Symbol	Value (hex)	Description
OP_0 or OP_FALSE	0x00	An empty array is pushed onto the stack
1 to 75	0x01 to 0x4b	Push the next N bytes onto the stack, where N is 1 to 75 bytes
OP_PUSHDATA1	0x4c	The next script byte contains N, push the following N bytes onto the stack
OP_PUSHDATA2	0x4d	The next two script bytes contain N, push the following N bytes onto the stack
OP_PUSHDATA4	0x4e	The next four script bytes contain N, push the following N bytes onto the stack
OP_1NEGATE	0x4f	Push the value "–1" onto the stack
OP_RESERVED	0x50	Halt—Invalid transaction unless found in an unexecuted OP_IF clause
OP_1 or OP_TRUE	0x51	Push the value "1" onto the stack
OP_2 to OP_16	0x52 to 0x60	For OP_N, push the value "N" onto the stack, e.g., OP_2 pushes "2"

Conditional flow control shows conditional flow control operators.

Table 2. Conditional flow control

Symbol	Value (hex)	Description
OP_NOP	0x61	Do nothing
OP_VER	0x62	Halt—Invalid transaction unless found in an unexecuted OP_IF clause
OP_IF	0x63	Execute the statements following if top of stack is not 0
OP_NOTIF	0x64	Execute the statements following if top of stack is 0
OP_VERIF	0x65	Halt—Invalid transaction
OP_VERNOTIF	0x66	Halt—Invalid transaction
OP_ELSE	0x67	Execute only if the previous statements were not executed
OP_ENDIF	0x68	End the OP_IF, OP_NOTIF, OP_ELSE block
OP_VERIFY	0x69	Check the top of the stack, halt and invalidate transaction if not TRUE
OP_RETURN	0x6a	Halt and invalidate transaction

Timelock operations shows operators used for timelocks.

Table 3. Timelock operations

Symbol	Value (hex)	Description
OP_CHECKLOCKTIMEVERIFY (previously OP_NOP2)	0xb1	Marks transaction as invalid if the top stack item is greater than the transaction’s nLockTime field, otherwise script evaluation continues as though an OP_NOP was executed. Transaction is also invalid if 1. the stack is empty; or 2. the top stack item is negative; or 3. the top stack item is greater than or equal to 500000000 while the transaction’s nLockTime field is less than 500000000, or vice versa; or 4. the input’s nSequence field is equal to 0xffffffff. The precise semantics are described in BIP-65
OP_CHECKSEQUENCEVERIFY (previously OP_NOP3)	0xb2	Marks transaction as invalid if the relative lock time of the input (enforced by BIP 0068 with nSequence) is not equal to or longer than the value of the top stack item. The precise semantics are described in BIP-112

Stack operations shows operators used to manipulate the stack.

Table 4. Stack operations

Symbol	Value (hex)	Description
OP_TOALTSTACK	0x6b	Pop top item from stack and push to alternative stack
OP_FROMALTSTACK	0x6c	Pop top item from alternative stack and push to stack
OP_2DROP	0x6d	Pop top two stack items
OP_2DUP	0x6e	Duplicate top two stack items
OP_3DUP	0x6f	Duplicate top three stack items
OP_2OVER	0x70	Copy the third and fourth items in the stack to the top
OP_2ROT	0x71	Move the fifth and sixth items in the stack to the top
OP_2SWAP	0x72	Swap the two top pairs of items in the stack
OP_IFDUP	0x73	Duplicate the top item in the stack if it is not 0
OP_DEPTH	0x74	Count the items on the stack and push the resulting count
OP_DROP	0x75	Pop the top item in the stack
OP_DUP	0x76	Duplicate the top item in the stack
OP_NIP	0x77	Pop the second item in the stack
OP_OVER	0x78	Copy the second item in the stack and push it onto the top
OP_PICK	0x79	Pop value N from top, then copy the Nth item to the top of the stack
OP_ROLL	0x7a	Pop value N from top, then move the Nth item to the top of the stack
OP_ROT	0x7b	Rotate the top three items in the stack
OP_SWAP	0x7c	Swap the top two items on the stack
OP_TUCK	0x7d	Copy the top item and insert it between the top and second item

String splice operations shows string operators.

Table 5. String splice operations

Symbol	Value (hex)	Description
OP_CAT	0x7e	Disabled (concatenates top two items)
OP_SUBSTR	0x7f	Disabled (returns substring)
OP_LEFT	0x80	Disabled (returns left substring)
OP_RIGHT	0x81	Disabled (returns right substring)
OP_SIZE	0x82	Calculate string length of top item and push the result

Binary arithmetic and conditionals shows binary arithmetic and boolean logic operators.

Table 6. Binary arithmetic and conditionals

Symbol	Value (hex)	Description
OP_INVERT	0x83	Disabled (Flip the bits of the top item)
OP_AND	0x84	Disabled (Boolean AND of two top items)
OP_OR	0x85	Disabled (Boolean OR of two top items)
OP_XOR	0x86	Disabled (Boolean XOR of two top items)
OP_EQUAL	0x87	Push TRUE (1) if top two items are exactly equal, push FALSE (0) otherwise
OP_EQUALVERIFY	0x88	Same as OP_EQUAL, but run OP_VERIFY after to halt if not TRUE
OP_RESERVED1	0x89	Halt—Invalid transaction unless found in an unexecuted OP_IF clause
OP_RESERVED2	0x8a	Halt—Invalid transaction unless found in an unexecuted OP_IF clause

Numeric operators shows numeric (arithmetic) operators.

Table 7. Numeric operators

Symbol	Value (hex)	Description
OP_1ADD	0x8b	Add 1 to the top item
OP_1SUB	0x8c	Subtract 1 from the top item
OP_2MUL	0x8d	Disabled (multiply top item by 2)
OP_2DIV	0x8e	Disabled (divide top item by 2)
OP_NEGATE	0x8f	Flip the sign of top item
OP_ABS	0x90	Change the sign of the top item to positive
OP_NOT	0x91	If top item is 0 or 1 Boolean flip it, otherwise return 0
OP_0NOTEQUAL	0x92	If top item is 0 return 0, otherwise return 1
OP_ADD	0x93	Pop top two items, add them and push result
OP_SUB	0x94	Pop top two items, subtract first from second, push result
OP_MUL	0x95	Disabled (multiply top two items)
OP_DIV	0x96	Disabled (divide second item by first item)
OP_MOD	0x97	Disabled (remainder divide second item by first item)
OP_LSHIFT	0x98	Disabled (shift second item left by first item number of bits)
OP_RSHIFT	0x99	Disabled (shift second item right by first item number of bits)
OP_BOOLAND	0x9a	Boolean AND of top two items
OP_BOOLOR	0x9b	Boolean OR of top two items
OP_NUMEQUAL	0x9c	Return TRUE if top two items are equal numbers
OP_NUMEQUALVERIFY	0x9d	Same as NUMEQUAL, then OP_VERIFY to halt if not TRUE
OP_NUMNOTEQUAL	0x9e	Return TRUE if top two items are not equal numbers
OP_LESSTHAN	0x9f	Return TRUE if second item is less than top item
OP_GREATERTHAN	0xa0	Return TRUE if second item is greater than top item
OP_LESSTHANOREQUAL	0xa1	Return TRUE if second item is less than or equal to top item
OP_GREATERTHANOREQUAL	0xa2	Return TRUE if second item is great than or equal to top item
OP_MIN	0xa3	Return the smaller of the two top items
OP_MAX	0xa4	Return the larger of the two top items
OP_WITHIN	0xa5	Return TRUE if the third item is between the second item (or equal) and first item

Cryptographic and hashing operations shows cryptographic function operators.

Table 8. Cryptographic and hashing operations

Symbol	Value (hex)	Description
OP_RIPEMD160	0xa6	Return RIPEMD160 hash of top item
OP_SHA1	0xa7	Return SHA1 hash of top item
OP_SHA256	0xa8	Return SHA256 hash of top item
OP_HASH160	0xa9	Return RIPEMD160(SHA256(x)) hash of top item
OP_HASH256	0xaa	Return SHA256(SHA256(x)) hash of top item
OP_CODESEPARATOR	0xab	Mark the beginning of signature-checked data
OP_CHECKSIG	0xac	Pop a public key and signature and validate the signature for the transaction’s hashed data, return TRUE if matching
OP_CHECKSIGVERIFY	0xad	Same as CHECKSIG, then OP_VERIFY to halt if not TRUE
OP_CHECKMULTISIG	0xae	Run CHECKSIG for each pair of signature and public key provided. All must match. Bug in implementation pops an extra value, prefix with OP_0 as workaround
OP_CHECKMULTISIGVERIFY	0xaf	Same as CHECKMULTISIG, then OP_VERIFY to halt if not TRUE

Nonoperators shows nonoperator symbols.

Table 9. Nonoperators

Symbol	Value (hex)	Description
OP_NOP1 to OP_NOP10	0xb0 to 0xb9	Does nothing, ignored

Reserved OP codes for internal use by the parser shows operator codes reserved for use by the internal script parser.

Table 10. Reserved OP codes for internal use by the parser

Symbol	Value (hex)	Description
OP_SMALLDATA	0xf9	Represents small data field
OP_SMALLINTEGER	0xfa	Represents small integer data field
OP_PUBKEYS	0xfb	Represents public key fields
OP_PUBKEYHASH	0xfd	Represents a public key hash field
OP_PUBKEY	0xfe	Represents a public key field
OP_INVALIDOPCODE	0xff	Represents any OP code not currently assigned